Systems and methods for transmitting signals in communication networks

1. A method of transmitting information via a communication network that comprises a plurality of nodes and a plurality of links between nodes, the plurality of links comprising at least one optical link and at least one wireless link, the method comprising: determining, for each path in a first plurality of paths in said communication network, a respective first weighted path length based at least in part on a number of pure wireless links in the path; selecting, from among the first plurality of paths, a second plurality of paths having first weighted path lengths less than a threshold value; determining, for each path in the second plurality, a respective second weighted path length based at least in part on a number of pure optical links in the path; selecting, from among the second plurality of paths, a transmission path having a highest second weighted path length; and transmitting information via the transmission path.

2. The method of claim 1 , wherein the communication network comprises a hybrid free-space optical/radio-frequency communication system.

3. The method of claim 1 , wherein the plurality of nodes comprises: at least one node comprising an RF transceiver and an optical transmitter; at least one node comprising an RF transceiver and an optical receiver; and at least one node comprising an RF transceiver and an optical transceiver.

4. The method of claim 1 , wherein the first weighted path length for a respective path equals w1*N(i)+(1−w1)*Nw(i), wherein w1 comprises a selected parameter, N(i) equals a total number of links in the respective path, and Nw(i) equals a number of pure wireless links in the respective path.

5. The method of claim 1 , wherein the threshold value equals min(Lw(i))*(1+k), wherein Lw(i) equals the first weighted path length of the respective path and k comprises a selected parameter.

6. The method of claim 1 , wherein the second weighted path length for a respective path equals w2*No(i)+(1−w2)*Now(i), wherein w2 comprises a selected parameter, No(i) equals a number of pure optical links in the respective path, and Now(i) equals a number of hybrid optical and wireless links in the respective path.

7. A method of transmitting information via a communication network that comprises a plurality of nodes and a plurality of links between nodes, the method comprising: for each path in a first plurality of paths in said communication network, performing the following steps: for each link in the respective path: determine a total effective link bandwidth value associated with the respective link; and determine a remaining link bandwidth value associated with the respective link, based on the total effective link bandwidth value associated with the respective link; and determine a remaining path bandwidth value associated with the respective path, based on the remaining link bandwidth values associated with the links in the respective path; selecting from the first plurality of paths a second plurality of paths having remaining path bandwidth values greater than a threshold value; selecting a transmission path from among the second plurality of paths based on one or more characteristics of the paths in the second plurality; and transmitting information via the selected transmission path.

8. The method of claim 1 , wherein the communication network comprises a hybrid free-space optical/radio-frequency communication system.

9. The method of claim 7 , wherein the remaining link bandwidth value associated with a respective link equals Br(ij)=Be(ij)−.SIGMA.R(ij,f), wherein Be(i,j) equals the total effective link bandwidth value associated with the respective link and R(i,j,f) is a data rate of a flow on the respective link.

10. The method of claim 9 , wherein the remaining path bandwidth value associated with a respective path equals the minimum remaining link bandwidth value among all the links in the respective path.

11. The method of claim 10 , wherein the threshold value equals a rate requested by a data flow.

12. The method of claim 7 , wherein the step of selecting a transmission path from among the second plurality of paths based on one or more characteristics of the paths in the second plurality comprises the following steps: determining, for each path in the second plurality of paths, a respective first weighted path length based at least in part on a number of pure wireless links in the path; selecting, from among the second plurality of paths, a third plurality of paths having first weighted path lengths less than a threshold value; determining, for each path in the third plurality, a respective second weighted path length based at least in part on a number of pure optical links in the path; and selecting, from among the third plurality of paths, a transmission path having a highest second weighted path length.

13. The method of claim 12 , wherein the first weighted path length for a respective path equals w1*N(i)−(1−w1)*Nw(i), wherein w1 comprises a first predetermined parameter, N(i) equals a total number of links in the respective path, and Nw(i) equals a number of pure wireless links in the respective path.

14. The method of claim 13 , wherein the threshold value equals min(Lw(i))*(1+k), wherein Lw(i) equals the first weighted path length of the respective path and k comprises a second predetermined parameter.

15. The method of claim 14 , wherein the second weighted path length for a respective path equals w2*No(i)−(1−w2)*Now(i), wherein w2 comprises a third predetermined parameter, No(i) equals a number of pure optical links in the respective path, and Now(i) equals a number of hybrid optical and wireless links in the respective path.

16. An apparatus for transmitting information via a communication network that comprises a plurality of nodes and a plurality of links between nodes, the plurality of links comprising at least one optical link and at least one wireless link, the apparatus comprising: means for determining, for each path in a first plurality of paths in said communication network, a respective first weighted path length based at least in part on a number of pure wireless links in the path; means for selecting, from among the first plurality of paths, a second plurality of paths having first weighted path lengths less than a threshold value; means for determining, for each path in the second plurality, a respective second weighted path length based at least in part on a number of pure optical links in the path; means for selecting, from among the second plurality of paths, a transmission path having a highest second weighted path length; and means for transmitting information via the transmission path.

17. The apparatus of claim 16 , wherein the communication network comprises a hybrid free-space optical/radio-frequency communication system.

18. The apparatus of claim 16 , wherein the plurality of nodes comprises: at least one node comprising an RF transceiver and an optical transmitter; at least one node comprising an RF transceiver and an optical receiver; and at least one node comprising an RF transceiver and an optical transceiver.

19. The apparatus of claim 16 , wherein the first weighted path length for a respective path equals w1*N(i)−(1−w1)*Nw(i), wherein w1 comprises a selected parameter, N(i) equals a total number of links in the respective path, and Nw(i) equals a number of pure wireless links in the respective path.

20. The apparatus of claim 16 , wherein the second weighted path length for a respective path equals w2*No(i)−(1−w2)*Now(i), wherein w2 comprises a selected parameter, No(i) equals a number of pure optical links in the respective path, and Now(i) equals a number of hybrid optical and wireless links in the respective path.